A randan is a boat

Boat

A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...

 rowed

Watercraft rowing

Watercraft rowing is the act of propelling a boat using the motion of oars in the water. The difference between paddling and rowing is that with rowing the oars have a mechanical connection with the boat whereas with paddling the paddles are hand-held with no mechanical connection.This article...

 by three persons, stern

Stern

The stern is the rear or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite of the bow, the foremost part of a ship. Originally, the term only referred to the aft port section...

 and bow

Bow (ship)

The bow is a nautical term that refers to the forward part of the hull of a ship or boat, the point that is most forward when the vessel is underway. Both of the adjectives fore and forward mean towards the bow...

 using a single oar

Oar

An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Oarsmen grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by...

 each and the central person a pair of sculls. The word is of unknown origin, and can hardly be connected with a slang

Slang

Slang is the use of informal words and expressions that are not considered standard in the speaker's language or dialect but are considered more acceptable when used socially. Slang is often to be found in areas of the lexicon that refer to things considered taboo...

 term for a row or spree

Spree

The Spree is a river that flows through the Saxony, Brandenburg and Berlin states of Germany, and in the Ústí nad Labem region of the Czech Republic...

, which is found as early as the beginning of the 18th century and is generally taken as a variation of random, haphazard.

Additionally in Scotland, the term out on the randan describes a night of drinking and/or socialising.

For example - "Awrite boys, gawn oot oan the randan the nite ?"

Randan is also a business in Middleton, Wisconsin, United States.